A Personal Digital Assistants (PDA) is a type of portable computer. The PDA refers to a portable information terminal capable of storing documents created using a computer. A PDA may be used for activities such as calculating, managing schedules, and the like. As information technology develops at a rapid pace, PDAs are increasingly popular among professionals that use the PDA's convenient features to manage information.
The PDA can process information which a user directly composes by hand as well as information downloaded from a computer, and provide to the user various information services such as on-line stock exchange, electronic commerce, and the like through a radio (wireless) communication.
A PDA type mobile communication terminal (e.g., a PDA phone) in which special functions are combined with a mobile communication terminal operates using an operating system similar to personal computers. As a result, a PDA phone is compatible with normal computers and can provide to users various services, such as traffic information as well as functions for wireless conversations and facsimile communication.
A hands-free device can be configured to connect to a PDA phone to allow the user communicate even when the phone is not held next to the user's ear. When a connector of a hands-free kit is connected or disconnected from a PDA phone, the PDA phone detects the connection state to establish an audio path. In ordinary electronic and electric equipment, the PDA phone uses an interrupt method or a polling method for detecting the connection state.
In the interrupt method, a processor receives a report for an interrupt generation while performing another operation. The processor stops its operation and activates a designated routine to accommodate the connection of the hands-free kit. Also, in the polling method, the processor periodically performs a separate scanning operation for detecting a new hardware, and when a new hardware is detected, the processor performs the designated routine.
A PDA phone according to the related art uses the polling method for polling a hands-free detection pin and an outer power detecting pin by a time period of 100 ms. Problems caused by using the related art PDA phone adapting the polling method will now be explained.
In general, portable terminals such as PDA phones or mobile communication terminals receive clocks from different clock sources depending on whether the mobile station modem is in a sleep state (i.e., sleep mode) or in a wake-up state (i.e., operating mode).
When the mobile station modem is in the sleep mode, the PDA phone receives a clock signal from a sleep crystal (32.768 KHz). Instead, when in the operating mode, the PDA phone receives the clock signal from a Temperature Compensated X-tal Oscillator (TCXO) crystal (19.68 MHz).
As a result of this dual synchronization mode, when the mobile station modem is in the sleep mode, the timing for detecting the hands-free kit is lengthened, due to a lower clock speed in comparison with a state when the mobile station modem is in the operating mode.
Moreover, when the related art PDA phone uses the polling method, if the hands-free kit is connected or disconnected very quickly, the related art mobile station modem in the sleep mode cannot sense the change of the state of the hands-free kit. This may result in an error in establishment of an audio path for the PDA phone.
A solution to the above problems is needed.